Merge pull request #11 from emirpasic/list_insert

List inserts

README.md

@@ -126,7 +126,7 @@ func main() {
 
 ####Lists
 
-A list is a data structure that can store elements and may have repeated values. There is no ordering in a list. The user can access and remove an element by the index position.
+A list is a data structure that can store values and may have repeated values. There is no ordering in a list. The user can access and remove a value by the index position.
 
 All lists implement the list interface with the following methods:
 
@@ -134,10 +134,11 @@ All lists implement the list interface with the following methods:
 type Interface interface {
     Get(index int) (interface{}, bool)
 	Remove(index int)
-	Add(elements ...interface{})
+	Add(values ...interface{})
-	Contains(elements ...interface{}) bool
+	Contains(values ...interface{}) bool
 	Sort(comparator utils.Comparator)
     Swap(index1, index2 int)
+   	Insert(index int, values ...interface{})
 
 	containers.Interface
 	// Empty() bool
@@ -180,12 +181,14 @@ func main() {
 	_ = list.Size()                       // 0
 	list.Add("a")                         // ["a"]
 	list.Clear()                          // []
+    list.Insert(0, "b")                   // ["b"]
+    list.Insert(0, "a")                   // ["a","b"]
 }
 ```
 
 #####SinglyLinkedList
 
-This structure implements the _List_ interface and is a linked data structure where each element points to the next in the list.
+This structure implements the _List_ interface and is a linked data structure where each value points to the next in the list.
 
 Direct access method _Get(index)_ and _Remove()_ are of linear performance. _Append_ and _Prepend_ are of constant time performance. Checking with _Contains()_ is of quadratic complexity.
 
@@ -215,12 +218,14 @@ func main() {
 	_ = list.Size()                       // 0
 	list.Add("a")                         // ["a"]
 	list.Clear()                          // []
+    list.Insert(0, "b")                   // ["b"]
+    list.Insert(0, "a")                   // ["a","b"]
 }
 ```
 
 #####DoublyLinkedList
 
-This structure implements the _List_ interface and is a linked data structure where each element points to the next and previous element in the list.
+This structure implements the _List_ interface and is a linked data structure where each value points to the next and previous element in the list.
 
 Direct access method _Get(index)_ and _Remove()_ are of linear performance. _Append_ and _Prepend_ are of constant time performance. Checking with _Contains()_ is of quadratic complexity.
 
@@ -250,6 +255,8 @@ func main() {
 	_ = list.Size()                       // 0
 	list.Add("a")                         // ["a"]
 	list.Clear()                          // []
+    list.Insert(0, "b")                   // ["b"]
+    list.Insert(0, "a")                   // ["a","b"]
 }
 ```
 

lists/arraylist/arraylist.go

@@ -57,10 +57,10 @@ func New() *List {
 }
 
 // Appends a value at the end of the list
-func (list *List) Add(elements ...interface{}) {
+func (list *List) Add(values ...interface{}) {
-	list.growBy(len(elements))
+	list.growBy(len(values))
-	for _, element := range elements {
+	for _, value := range values {
-		list.elements[list.size] = element
+		list.elements[list.size] = value
 		list.size += 1
 	}
 }
@@ -94,12 +94,12 @@ func (list *List) Remove(index int) {
 // All elements have to be present in the set for the method to return true.
 // Performance time complexity of n^2.
 // Returns true if no arguments are passed at all, i.e. set is always super-set of empty set.
-func (list *List) Contains(elements ...interface{}) bool {
+func (list *List) Contains(values ...interface{}) bool {
 
-	for _, searchElement := range elements {
+	for _, searchValue := range values {
 		found := false
 		for _, element := range list.elements {
-			if element == searchElement {
+			if element == searchValue {
 				found = true
 				break
 			}
@@ -142,13 +142,39 @@ func (list *List) Sort(comparator utils.Comparator) {
 	utils.Sort(list.elements[:list.size], comparator)
 }
 
-// Swaps values of two elements at the given indices.
+// Swaps the two values at the specified positions.
 func (list *List) Swap(i, j int) {
 	if list.withinRange(i) && list.withinRange(j) {
 		list.elements[i], list.elements[j] = list.elements[j], list.elements[i]
 	}
 }
 
+// Inserts values at specified index position shifting the value at that position (if any) and any subsequent elements to the right.
+// Does not do anything if position is negative or bigger than list's size
+// Note: position equal to list's size is valid, i.e. append.
+func (list *List) Insert(index int, values ...interface{}) {
+
+	if !list.withinRange(index) {
+		// Append
+		if index == list.size {
+			list.Add(values...)
+		}
+		return
+	}
+
+	l := len(values)
+	list.growBy(l)
+	list.size += l
+	// Shift old to right
+	for i := list.size - 1; i >= index+l; i-- {
+		list.elements[i] = list.elements[i-l]
+	}
+	// Insert new
+	for i, value := range values {
+		list.elements[index+i] = value
+	}
+}
+
 func (list *List) String() string {
 	str := "ArrayList\n"
 	values := []string{}
@@ -161,7 +187,7 @@ func (list *List) String() string {
 
 // Check that the index is withing bounds of the list
 func (list *List) withinRange(index int) bool {
-	return index >= 0 && index < list.size && list.size != 0
+	return index >= 0 && index < list.size
 }
 
 func (list *List) resize(cap int) {

lists/arraylist/arraylist_test.go

@@ -27,6 +27,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 package arraylist
 
 import (
+	"fmt"
 	"github.com/emirpasic/gods/utils"
 	"testing"
 )
@@ -120,6 +121,19 @@ func TestArrayList(t *testing.T) {
 		t.Errorf("Got %v expected %v", actualValue, true)
 	}
 
+	list.Insert(0, "h")
+	list.Insert(0, "e")
+	list.Insert(1, "f")
+	list.Insert(2, "g")
+	list.Insert(4, "i")
+	list.Insert(0, "a", "b")
+	list.Insert(list.Size(), "j", "k")
+	list.Insert(2, "c", "d")
+
+	if actualValue, expectedValue := fmt.Sprintf("%s%s%s%s%s%s%s%s%s%s%s", list.Values()...), "abcdefghijk"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+
 }
 
 func BenchmarkArrayList(b *testing.B) {

lists/doublylinkedlist/doublylinkedlist.go

@@ -244,6 +244,60 @@ func (list *List) Swap(i, j int) {
 	}
 }
 
+// Inserts values at specified index position shifting the value at that position (if any) and any subsequent elements to the right.
+// Does not do anything if position is negative or bigger than list's size
+// Note: position equal to list's size is valid, i.e. append.
+func (list *List) Insert(index int, values ...interface{}) {
+
+	if !list.withinRange(index) {
+		// Append
+		if index == list.size {
+			list.Add(values...)
+		}
+		fmt.Println(list.Values())
+		return
+	}
+
+	list.size += len(values)
+
+	var beforeElement *element
+	var foundElement *element
+	// determine traversal direction, last to first or first to last
+	if list.size-index < index {
+		foundElement = list.last
+		for e := list.size - 1; e != index; e, foundElement = e-1, foundElement.prev {
+			beforeElement = foundElement.prev
+		}
+	} else {
+		foundElement = list.first
+		for e := 0; e != index; e, foundElement = e+1, foundElement.next {
+			beforeElement = foundElement
+		}
+	}
+
+	if foundElement == list.first {
+		oldNextElement := list.first
+		for i, value := range values {
+			newElement := &element{value: value}
+			if i == 0 {
+				list.first = newElement
+			} else {
+				beforeElement.next = newElement
+			}
+			beforeElement = newElement
+		}
+		beforeElement.next = oldNextElement
+	} else {
+		oldNextElement := beforeElement.next
+		for _, value := range values {
+			newElement := &element{value: value}
+			beforeElement.next = newElement
+			beforeElement = newElement
+		}
+		beforeElement.next = oldNextElement
+	}
+}
+
 func (list *List) String() string {
 	str := "DoublyLinkedList\n"
 	values := []string{}
@@ -256,5 +310,5 @@ func (list *List) String() string {
 
 // Check that the index is withing bounds of the list
 func (list *List) withinRange(index int) bool {
-	return index >= 0 && index < list.size && list.size != 0
+	return index >= 0 && index < list.size
 }

lists/doublylinkedlist/doublylinkedlist_test.go

@@ -27,6 +27,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 package doublylinkedlist
 
 import (
+	"fmt"
 	"github.com/emirpasic/gods/utils"
 	"testing"
 )
@@ -122,6 +123,19 @@ func TestDoublyLinkedList(t *testing.T) {
 		t.Errorf("Got %v expected %v", actualValue, true)
 	}
 
+	list.Insert(0, "h")
+	list.Insert(0, "e")
+	list.Insert(1, "f")
+	list.Insert(2, "g")
+	list.Insert(4, "i")
+	list.Insert(0, "a", "b")
+	list.Insert(list.Size(), "j", "k")
+	list.Insert(2, "c", "d")
+
+	if actualValue, expectedValue := fmt.Sprintf("%s%s%s%s%s%s%s%s%s%s%s", list.Values()...), "abcdefghijk"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+
 }
 
 func BenchmarkDoublyLinkedList(b *testing.B) {

lists/lists.go

@@ -26,10 +26,11 @@ import (
 type Interface interface {
 	Get(index int) (interface{}, bool)
 	Remove(index int)
-	Add(elements ...interface{})
+	Add(values ...interface{})
-	Contains(elements ...interface{}) bool
+	Contains(values ...interface{}) bool
 	Sort(comparator utils.Comparator)
 	Swap(index1, index2 int)
+	Insert(index int, values ...interface{})
 
 	containers.Interface
 	// Empty() bool

lists/singlylinkedlist/singlylinkedlist.go

@@ -223,6 +223,51 @@ func (list *List) Swap(i, j int) {
 	}
 }
 
+// Inserts values at specified index position shifting the value at that position (if any) and any subsequent elements to the right.
+// Does not do anything if position is negative or bigger than list's size
+// Note: position equal to list's size is valid, i.e. append.
+func (list *List) Insert(index int, values ...interface{}) {
+
+	if !list.withinRange(index) {
+		// Append
+		if index == list.size {
+			list.Add(values...)
+		}
+		fmt.Println(list.Values())
+		return
+	}
+
+	list.size += len(values)
+
+	var beforeElement *element
+	foundElement := list.first
+	for e := 0; e != index; e, foundElement = e+1, foundElement.next {
+		beforeElement = foundElement
+	}
+
+	if foundElement == list.first {
+		oldNextElement := list.first
+		for i, value := range values {
+			newElement := &element{value: value}
+			if i == 0 {
+				list.first = newElement
+			} else {
+				beforeElement.next = newElement
+			}
+			beforeElement = newElement
+		}
+		beforeElement.next = oldNextElement
+	} else {
+		oldNextElement := beforeElement.next
+		for _, value := range values {
+			newElement := &element{value: value}
+			beforeElement.next = newElement
+			beforeElement = newElement
+		}
+		beforeElement.next = oldNextElement
+	}
+}
+
 func (list *List) String() string {
 	str := "SinglyLinkedList\n"
 	values := []string{}
@@ -235,5 +280,5 @@ func (list *List) String() string {
 
 // Check that the index is withing bounds of the list
 func (list *List) withinRange(index int) bool {
-	return index >= 0 && index < list.size && list.size != 0
+	return index >= 0 && index < list.size
 }

lists/singlylinkedlist/singlylinkedlist_test.go

@@ -27,6 +27,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 package singlylinkedlist
 
 import (
+	"fmt"
 	"github.com/emirpasic/gods/utils"
 	"testing"
 )
@@ -122,6 +123,19 @@ func TestSinglyLinkedList(t *testing.T) {
 		t.Errorf("Got %v expected %v", actualValue, true)
 	}
 
+	list.Insert(0, "h")
+	list.Insert(0, "e")
+	list.Insert(1, "f")
+	list.Insert(2, "g")
+	list.Insert(4, "i")
+	list.Insert(0, "a", "b")
+	list.Insert(list.Size(), "j", "k")
+	list.Insert(2, "c", "d")
+
+	if actualValue, expectedValue := fmt.Sprintf("%s%s%s%s%s%s%s%s%s%s%s", list.Values()...), "abcdefghijk"; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+
 }
 
 func BenchmarkSinglyLinkedList(b *testing.B) {